Mandrel



A ril 16, 1940.

H. DAVIS ET AL MANDREL Filed Dec. 7, 1936 0 0 m%% .H 1%. m5 HJ.

Patented Apr. 16, 1%40 watt PATENT orrica MANDREL Herbert Davis,Cleveland,

Ohio, and Joseph Pawol, Ellwood City, Pa., assignors to National TubeCompany, a corporation of New Jersey Application December 7, 1936,Serial No. 114,714

5 Claims.

This invention relates to mandrels for metalworking operations and moreparticularly topiercing points and plugs for use in seamless tube mills.

fore, it has been impossible to successfully pierce solid billets madeof high-chromium and highchromium-nickel alloys of the .stainless type,with piercing points made of low-chromiumnickel alloys. The conventionalchromium-nickel piercing. points, upon repeated usage on short lengthbillets; or single usage on long lengths of plain or alloy tubing; orsingle usage on stainless steel, fail by either distorting, burning onthe nose, welding to the billet, picking-up metal or cracking from heat.The change in contour materially affects the quality of billetprocessed, power required, and may at times stall the machine and resultin material damage.

Further, it has been impossible to use this conventional type 01'piercing point metal analysis on rotary rolling-mills or Stiefelexpandingmills, wherein a finished wall-size isobtained, due to thenecessity and difiiculty of machining the plugs to a close tolerance.

The novel mandrel of this invention is especially adaptable for use as apoint or plug for piercing all workable plain and alloy steels or metalswith a substantial increase in service over the chromium-nickel alloypiercing points heretofore used for both plain and alloy tubing.

The scaling and, physical properties of this alloy mandrel, piercingpoint or plug are, upon heat-treatment, of such character that it iscapable of withstanding highthermal shock without deforming, welding,cracking or otherwise becoming useless for more than one operation in asequence. This has been impossible with the high alloy type of toolsheretofore used for piercing alloy steels of the high-chromium andhigh-chromium-nickel type, as this type of piercing point or plugrequires preheating before use to reduce the thermal shock, andwascapable of piercing only one piece of material before deforming, weldingor cracking, which renders it unfit for further use.

The physical properties of this alloy when properly heat-treated areexceptionally good, and

heat-treated tools formed of' this alloy may be shaped, forged,machined, ground or otherwise hot or cold formed without material changeof its properties. These properties render the alloy adaptable forrotary rolling mill plugs which must be machined to a close tolerance.

Furthermore, with proper heat treatment, this alloy is free from hot orcold shortness and also from the so-called blue brittleness. which haslong been the bane of points cast from the conventional chromium-nickelalloy irons or steels.

In the manufactureof pipes and tubes hereto- The scaling properties ofthis alloy mandrel are Iar superior to the chromium-nickel alloy type.When properly heat-treated, the scale is or a heavy, tightly adherentnature that Will not all oil in ordinary handling and, due to a uniqueproperty of the scale, when the tool is used it melts or fuses into ahard blue-black lustrous metallic coating which protects the tool duringsubsequent uses. I

The above and further objects will bu me apparent by referring to thefollowing description and the accompanying drawing, in which:

Figures 1 through 6 are plans of pipe or tube mill piercing points whichmay be composed of the alloy of the present invention.

The piercing point or plug A of Figure l is of a type for use with athirty-six inch roll piercing mill. The point A is composed of anintegral casting of the special alloy to be described below andcomprises a point portion 2, a tapered body portion 3, and a sleeve orneck portion l of less diameter than the body and adapted to receive theforward end of the plug-bar of the mill.

The piercing point or plug B of Figure 2 is another type ior use withthe thirty-six inch roll piercing mill. The point B is generally of asmaller diameter than the point A and is for piercing smaller billets.The point B consists of a tapered body 5 and a neck or sleeve 6 having acore 1 which is extended into the body portion to receive the end of theplug-bar.

The plug or point C of Figure 3 is for use with a disk type of piercingmill and comprises a long tapered nose portion 9 and a body-portion Illcomposed of a relatively short straight portion I2 and a rearwardlytapered portion l3. The

portion I3 is provided with a core [4 to receive the end of the usualplug-bar.

The plug or point D of Figure 4 is for use on a rotary rolling mill orStiefel type cone ex- .pander and comprises an angular inlet section 5,a rolling section it and a cylindrical section H. The tool has a coredinlet i8, outlet i9 and chamber 2@. The cored section receives the plugsupporting mandrel.

The plug or point E of Figure 5 consists of a curvilinear inlet orworking section iii, a relief section 22 and core 23 to receive the barcap.

The plug or point F of Figure 6 consists of a curvilinear inlet orworking section 2 1, a relief section 25 and a chamber core section itto receive the bar and reduce the weight.

Plugs or points like the foregoing, or any other design of plug orpoint, for seamless mill operations, when made in accordance with thisinvention, are particularly adapted for processing plain orhigh-chromium or high chromiumnickel steel alloys of the stainless typeor other alloy tubing.

Per cent Carbon .15 to .50 Manganese .40 to 1.50 Silicon .40 to 1.50Chromium .50 to 2.50 Cobalt .50 to 2.50. Copper .50 to 2.50 Nickel .05to 2.50' Phosphorus under .06 Sulphur under .06 Iron to make' 100.00

The plugs or points of this invention are cast from an alloy having thefollowing range of analysis:

Other elements such as aluminum, titanium, zirconium, molybdenum,tungsten or vanadium may be added as desired.

A preferred specific alloy for the plugs or points has the followinganalysis:

Per cent Carbon .20 Manganese .75 Silicon 1.00 Chromium a 1.50 Cobalt1.00 Copper 1.00 Nickel .50 Phosphorus .01 Sulphur .01 Iron to make100.00

After the points or plugs are cast from the alloy above set forth, theyare heat-treated by annealing in a closed furnace at a temperaturebetween 900 degrees to 1000 degrees centigrade and preferably atapproximately 950 degrees centigrade for approximately five hours andslowly cooled in the furnace. This heat treatment materially increasesthe physical properties of the points or plugs and forms thereon a closeanalysis:

Per cent Carbon .15 to .50 Manganese .40 to 1.50 Silicon .40 to 1:50Chromium .50 to 2.50 Cobalt .50 to 2.50 Copper .50 to 2.50 Nickel .05 to2.50 Phosphorus under.... .06 Sulphur under .06 Ir n Remainder annealingsaid piercing point at a temperature between 900 degrees and 1000degrees centigrade and slowly cooling the same, whereby there is formeda. tightly adherent scale which melts or fuses when the piercing pointis used.

2. The method of making a piercing point for tube mills which includescasting said piercing point from a ferrous alloy having the followinganalysis:

' annealing said piercing point at a temperature between 900 degrees and1000 degrees centigrade and slowly cooling the same, whereby there isformed atightly adherent scale which melts or fuses when the piercingpoint is used.

3.The method-of making a piercing point for tube mills which includescasting said piercing point from a'ferrous alloy having the followinganalysis:

Per cent Carbon .15 to .50 Manganese .40 to 1.50 Silicon .40 to 1.50Chromium .50 to 2.50 Cobalt r .50to' 2.50 C opper .50 to 2.50 Nickel;.05 to 2.50 Phosphorus under .06 Sulphur under .06 Iron; Remainderannealing said piercing point at a temperature of approximately 950degrees centigrade and slowly cooling the same, whereby there is formeda tightly adherent scale which melts or fuses when the piercing point isused. 1

4. The method of making a piercing point for tube mills which includescasting said piercing point from a ferrous alloy having the followinganalysis: Per cent Carbon approximately Manganese approximately .75Silicon approximately"--- 1.00 Chromium approximately 1.50 Cobaltapproximately 1.00 Copper approximately 1.00 Nickel approximately .50Phosphorus under .06 Sulphur under .06 Iron Remainder annealing saidpiercing point at a temperature of approximately 950 .degrees centigradeand slowly cooling the same, whereby there is formed a tightly adherentscale which melts or fuses when the piercing point is used.

5. The method of making a piercing point for tube mills which'includescasting said piercing point from a ferrous alloy having the followinganalysis:

Per cent Carbon .15 to .50 Manganese .40 to 1.50 Silicon .40 to 1.50Chromium .510 to 2.50 Cobalt .50 to 2.50 Copper .50 to 2.50 Nickel .05to 2.50 Phosphorus under .06 Sulphur under .06

Iron Remainder annealing said piercing point, and slowly cooling thesame, whereby there is formed a tightly adherent scale which melts orfuses when the viewing is used- JOSEPH PAWOL.

HERBERT DAVIS.

' Percent Carbon approximately .20 Manganese approximately .75 Siliconapproximately; 1.00 Chromium approximately 1.50 Cobalt approximately1.00

Copper approximately 1.00 Nickel approximately .50 Phosphorus under L..06 Sulphur under .06 Iron". Remainder

